172 BEGINNINGS OF INTELLIGENCE 



shall therefore consider the question purely from a phy- 

 siological standpoint. Viewed objectively we find that 

 in an animal's behavior certain acts when once performed 

 tend to be performed with greater readiness under similar 

 conditions a second time, while other acts once performed 

 tend under similar conditions to be inhibited. This prob- 

 lem of learning, Baldwin observes "is the most urgent, 

 difficult and neglected question in the new genetic psychol- 

 ogy." Spencer with his characteristic insight into funda- 

 mental problems has grappled with it and has attempted 

 to give a physiological explanation. Pleasure, according 

 to Spencer, is the concomitant of heightened nervous dis- 

 charge; pain the concomitant of lessened discharge. In an 

 animal with a diffuse discharge of its nervous energy result- 

 ing in random movements, some of these movements bring 

 a heightened nervous discharge with its psychic accompani- 

 ment of pleasure. This tends to reinforce the movement that 

 brought the increase of nervous energy and to cause it to be 

 repeated. Responses resulting in pain tend on account of the 

 diminution of nervous discharge that follows to be discon- 

 tinued, and in this way the organism is kept repeating certain 

 acts and avoiding others. "Along with the concentrated 

 discharge to particular muscles," says Spencer, "the gang- 

 lionic plexuses inevitably carry off a certain diffused dis- 

 charge to the muscles at large, and this diffused discharge 

 produces on them very variable results. Suppose, now, 

 that in putting out its head to seize prey scarcely within 

 reach, a creature has repeatedly failed. Suppose that along 

 with the group of motor actions approximately adapted to 

 seize prey at this distance, the diffused discharge is, on 

 some occasion, so distributed throughout the muscular 

 system as to cause a slight forward movement of the body. 

 Success will occur instead of failure; and after success will 



